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Eric
99 lines
5.1 KiB
YAML
99 lines
5.1 KiB
YAML
name: WinRAR Spawning Shell Application
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id: d2f36034-37fa-4bd4-8801-26807c15540f
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version: 9
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date: '2025-05-02'
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author: Michael Haag, Splunk
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status: production
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type: TTP
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data_source:
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- Sysmon EventID 1
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- Windows Event Log Security 4688
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- CrowdStrike ProcessRollup2
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description: The following analytic detects the execution of Windows shell processes
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initiated by WinRAR, such as "cmd.exe", "powershell.exe", "certutil.exe", "mshta.exe",
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or "bitsadmin.exe". This detection leverages data from Endpoint Detection and Response
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(EDR) agents, focusing on process and parent process relationships. This activity
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is significant because it may indicate exploitation of the WinRAR CVE-2023-38831
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vulnerability, where malicious scripts are executed from spoofed ZIP archives. If
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confirmed malicious, this could lead to unauthorized access, financial loss, and
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further malicious activities like data theft or ransomware attacks.
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search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
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as lastTime from datamodel=Endpoint.Processes where Processes.parent_process_name=winrar.exe
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`windows_shells` OR Processes.process_name IN ("certutil.exe","mshta.exe","bitsadmin.exe")
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by Processes.action Processes.dest Processes.original_file_name Processes.parent_process
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Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id
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Processes.parent_process_name Processes.parent_process_path Processes.process Processes.process_exec
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Processes.process_guid Processes.process_hash Processes.process_id Processes.process_integrity_level
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Processes.process_name Processes.process_path Processes.user Processes.user_id Processes.vendor_product
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| `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`
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| `winrar_spawning_shell_application_filter`'
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how_to_implement: The detection is based on data that originates from Endpoint Detection
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and Response (EDR) agents. These agents are designed to provide security-related
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telemetry from the endpoints where the agent is installed. To implement this search,
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you must ingest logs that contain the process GUID, process name, and parent process.
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Additionally, you must ingest complete command-line executions. These logs must
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be processed using the appropriate Splunk Technology Add-ons that are specific to
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the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint`
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data model. Use the Splunk Common Information Model (CIM) to normalize the field
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names and speed up the data modeling process.
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known_false_positives: Be aware of potential false positives - legitimate uses of
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WinRAR and the listed processes in your environment may cause benign activities
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to be flagged. Upon triage, review the destination, user, parent process, and process
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name involved in the flagged activity. Capture and inspect any relevant on-disk
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artifacts, and look for concurrent processes to identify the attack source. This
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approach helps analysts detect potential threats earlier and mitigate the risks.
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references:
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- https://www.group-ib.com/blog/cve-2023-38831-winrar-zero-day/
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- https://github.com/BoredHackerBlog/winrar_CVE-2023-38831_lazy_poc
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- https://github.com/b1tg/CVE-2023-38831-winrar-exploit
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drilldown_searches:
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- name: View the detection results for - "$user$" and "$dest$"
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search: '%original_detection_search% | search user = "$user$" dest = "$dest$"'
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earliest_offset: $info_min_time$
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latest_offset: $info_max_time$
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- name: View risk events for the last 7 days for - "$user$" and "$dest$"
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search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$",
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"$dest$") starthoursago=168 | stats count min(_time) as firstTime max(_time)
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as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk
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Message" values(analyticstories) as "Analytic Stories" values(annotations._all)
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as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics"
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by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
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earliest_offset: $info_min_time$
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latest_offset: $info_max_time$
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rba:
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message: An instance of $parent_process_name$ spawning $process_name$ was identified
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on endpoint $dest$ by user $user$ attempting to decode a file.
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risk_objects:
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- field: user
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type: user
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score: 70
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- field: dest
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type: system
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score: 70
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threat_objects:
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- field: parent_process_name
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type: parent_process_name
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- field: process_name
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type: process_name
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tags:
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analytic_story:
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- Compromised Windows Host
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- WinRAR Spoofing Attack CVE-2023-38831
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cve:
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- CVE-2023-38831
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asset_type: Endpoint
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atomic_guid: []
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mitre_attack_id:
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- T1105
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product:
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- Splunk Enterprise
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- Splunk Enterprise Security
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- Splunk Cloud
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security_domain: endpoint
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tests:
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- name: True Positive Test
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attack_data:
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- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1105/atomic_red_team/winrar.log
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source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
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sourcetype: XmlWinEventLog
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